1. Field of the Invention
This invention relates to a roaming method for maintaining connectivity between a client and a server of a system through heterogeneous wireless networks.
2. Description of the Related Art
A conventional wireless device, such as a mobile phone or a personal digital assistant (PDA), that supports internet protocol (IP) connectivity is currently available in the marketplace. In a conventional method, such as the Mobile IP protocol, for maintaining an IP connectivity, the conventional wireless device uses two IP addresses, namely a home address and a care-of address, and requires the existence of a home agent and a foreign agent. The home address makes the conventional wireless device logically attached to its home network. When the conventional wireless device is not attached to its home network, and is therefore attached to a foreign network, the conventional wireless device is assigned with the care-of address. Whenever the conventional wireless device moves, the conventional wireless device registers its new care-of address to its home agent. To receive data packets, the home agent receives all the data packets destined for the wireless device via the home address, and delivers the data packets to the foreign network via the care-of address.
The aforementioned conventional method is disadvantageous in that the data packets are not directly sent to the conventional wireless device, and is applicable only for an IP-based wireless network.